In this chapter many experimental conditions in relation to feeding have been discussed and advantages/disadvantages for animal welfare have been evaluated. What implications do they have for research on animals with regard to the animals welfare and the standardisation of experimental results?

Providing animals with food that fulfils their species-specific nutrient needs is a necessary item for securing basal welfare and reliable experimental results. However, in what way we need to provide the food in order to maintain or increase animal welfare is an important question. Is it enough to fulfil essential nutrient needs, or do we need to do more? Is it important for the animal to have the possibility to select from various food items, i.e. have more influence on composing the diets themselves? When rats were offered various diets differing in macronutrient composition, their preference varied with the time of the night. This is an indication that the needs may vary during the circadian cycle. More investigations are needed to solve whether self-selection of food is important for animal health and welfare. Whether it is important for the animals’ well-being to work for obtaining food, remains a subject of debate. When given the choice, domesticated chickens clearly show a lower preference for obtaining food by working for it as compared to their wild ancestors. However, the percentage of food obtained by working is still 30%. Results from preference tests with rats give the same result. This indicates that animals in captivity still like to work for food, at least to a certain extent. The method that can be used to make animals work for food will depend on the species-specific behaviour and needs. In case a method is chosen, it is not certain that it will remain satisfactory as it can quickly loose its novelty value as was shown in the example where rats initially had to increase their efforts for obtaining food through narrowed distance between food hopper bars.

As ad libitum feeding in long-term toxicity studies have been clearly associated with negative health effects, restricted feeding is advised. How and when to feed is important for the animals' welfare, as e.g. the frequency of stereotyped behaviour in rabbits is increased when they are fed ad libitum or restrictedly at an “unnatural” time point of day as compared to restricted feeding at a “natural” time point (just before the dark phase). Stereotyped behaviour will induce increased variation in results, as the degree of behaviour will vary for each individual and thereby the effects on energy utilisation. We believe that an adaptation of feeding schedules to the normal circadian patterns will contribute positively to welfare as well as standardisation of results. Feeding at “unnatural” times will cause wider fluctuation and perturbed physiology and will bring animals out of homeostasis, thereby decreasing welfare. Although group housing of social species is preferred over individual housing, it may be unpractical (e.g.

catheterized animals, aggressive males) and a source of unwanted extra variance. Dependent on the species, sex, experimental goals, etc. groups should be composed and monitored carefully, as group composition and behaviour can compromise standardisation and welfare.

Whether variation in food items provided is an essential factor to increase welfare is a matter of debate. Providing this dietary variation may be in conflict with the striving for standardisation of results, as the choice of individuals may be different. Also the choice of individuals during the circadian cycle may vary, contributing to a higher variation in experimental results. An indirect indication of how animals subjectively value the provision of food variation is obtained in preference testing, also involving the level of effort animals are willing to invest for obtaining this goal. By evaluating the level of investment an animal is willing to give, an indication of the motivation to reach a certain goal can be obtained.

Trying to improve welfare and fulfilling the animals' needs for a good welfare may give a potential conflict with trying to standardise experiments and reducing variation in results. On the other hand, an improved welfare may also lead to an animal that is more in balance physiologically and psychologically, thereby resulting in reduced variation as it can cope better with environmental challenges. This will depend on the circumstances and parameters measured. By carefully monitoring the animals' species-specific physiology and behaviour in experimental studies exploring the relation between nutritional factors, welfare and variation in results, more insight into these factors can be obtained.


Al-Modhefer AKJ, Atherton JC, Garland HO, Singh HJ, Walker J. Kidney function in rats with corticomedullary nephrocalcinosis: effects of alterations in dietary calcium and magnesium. J Physiol 1986; 380:405-414

Balkan B, Steffens AB, Bruggink JE, Strubbe JH. Hyperinsulinemia and glucose tolerance in VMH-lesioned obese rats: Dependence on food intake and route of administration.

Metabolism 1991; 49:1092-1100

Beynen AC, Coates ME. Nutrition and experimental results. In Principles of Laboratory Animal Science. Bert FM, van Zutphen LFM, Baumans V, Beynen AC eds, Elsevier Scientific Publishers, Amsterdam 2001; 111-128

Brinkhof MWG, Daan S, Strubbe JH. Forced dissociation of food and light-entrainable circadian rhythms of rats in a skeleton photoperiod. Physiol Behav 1998; 65:225-231 British Association of Research Quality Assurance (BARQA). Guidelines for the manufacture

and supply of GLP animal diets. 1992

Broom DM (ed.). Coping with Challenge. Dahlem University Press, Berlin 2001

Buwalda B, Blom WAM, Koolhaas JM, van Dijk GJ. Behavioral and physiological responses to stress are affected by high-fat feeding in male rats. Physiol Behav 2001; 73:371-377 Carter CS, Fraser D, Gartner K, Lutgendorf SK, Mineka S, Panksepp J, Sachser N. “Group

report: Good welfare. Improving quality of life”. In Coping with Challenge. Broom DM ed, Dahlem University Press, Berlin 2001; 79-100

Chevdoff M, Clarke MR, Faccini JM, Irisarri E, Monro AM. Effects on mice of number of animals per cage: an 18-month study (preliminary results). Arch Toxicol 1980;


Claassen V. Neglected Factors in Pharmacology and Neuroscience Research. Elsevier, Amsterdam 1994

Crok M. Bij de beesten af. Natuur en Techniek 2003; 4:46-48

De Wille JW, Waddell K, Steinmeyer C, Farmer ST. Dietary fat promotes mammary tumorigenesis in MMTV/v-Ha-ras transgenic mice. Cancer Lett 1993; 69:59-66

Environmental Protection Agency. Proposed health effects test standards for toxic substances control act test rules, Good laboratory standards for health effects in Federal Register, 1979; vol 44, no. 91

Ewen SWB, Pusztai A. Effect of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine. Lancet 1999; 354:1353-1354

Fraser D, Weary DM, Pajor EA, Milligan BN. A scientific conception of animal welfare that reflects ethical concerns. Anim Welf 1997; 6:187-205

Gartner K. Good, basal and poor welfare of laboratory animals. Different contributions of behavioural patterns (poster). 8th FELASA symposium, Aachen, June 2002

GV-Solas. Guidelines for the Quality-assured production of laboratory animal diets.

Gesellschaft für Versuchstierkunde – German Society for Laboratory Animal Science 2002

Hart RW, Neumann DA, Robertson RT eds. Dietary Restriction: Implications for the Design and Interpretation of Toxicity and Carcinogenicity Studies. ILSI Press, Washington 1995 Haseman JK, Huff J, Boorman GA. Use of historical control data in carcinogenicity studies in

rodents. Toxicol Pathol 1984; 12:126-135

Hornicke H, Ruoff G, Vogt B, Clauss W, Ehrlein H-J. Phase relationship of the circadian rhythms of feed intake, caecal motility and production of soft and hard faeces in domestic rabbits. Lab Anim 1984; 18:169-172

Jayo JM, Schwenke DC, Clarkson TB. Atherosclerosis research. In The Biology of the Laboratory Rabbit, 2nd Edition. Manning PJ, Ringler DH, Newcomer CE eds, Academic Press, san Diego 1994; 367-380

Jensen P. Behaviour, stress and welfare – genetic and phenotypic side-effects of selection for production traits (presentation). Symposium “Grenzen aan welzijn & dierlijke productie”.

Utrecht, April 10, 2003

Kaufman LW, Collier G. The economics of seed handling. Am Nat 1981; 118:46-60

Keenan KP, Ballam GC, Soper KA, Laroque P, Coleman J.B, Dixit R. Diet, caloric restriction, and the rodent bioassay. Toxicol Sci 1999; 52(2 Suppl):24-34

Krohn TC, Ritskes-Hoitinga J, Svendsen P. The effects of feeding and housing on the behaviour of the laboratory rabbit. Lab Anim 1999; 33:101-107

Moazed TC. Continuing Education Seminar, The American Society of Laboratory Animal Practitioners. October 1998, Cincinnati, USA

National Research Council (NRC). Nutrient Requirements of Sheep 1985; of Dogs 1985; of Beef Cattle 1984; of Mink and Foxes, 1982; of Laboratory Animals (Rat, Mouse, Guinea pig, Hamster, Gerbil, Vole), 1995; of Poultry 1994; of Fish 1993; of Horses 1989; of Dairy Cattle 1989; of Swine 1998; of Cats 1986; of Goats 1981; of Nonhuman Primates 1978; of Rabbits 1977. National Academy Press, Washington DC

Nott HMR, Sibly RM. Responses to novel food by rats: the effect of social rank. Crop Prot 1993; 12:89-94

Peters A, Festing M. Population density and growth rate in laboratory mice. Lab Anim 1990;


Reeves PhG, Nielsen FH, Fahey GCJr. AIN-93 purified diets for laboratory rodents: final report of the American Institute of Nutrition Ad Hoc writing committee on the reformulation of the AIN-76A rodent diet. J Nutr 1993; 123:1939-1951

Ritskes-Hoitinga J, Beynen AC. Nephrocalcinosis in the rat: a literature review. Prog Food Nutr Sci 1992; 16:85-124

Ritskes-Hoitinga J, Schledermann C. A pilot study into the effects of various dietary restriction schedules in rabbits. Scand J Lab Anim Sci 1999; 26:66-74

Ritskes-Hoitinga J, Chwalibog A. “Nutrient Requirements, experimental design and feeding schedules in animal experimentation.” In Handbook of Laboratory Animal Science. Hau J, Hoosier GL eds, CRC Press, Boca Raton 2003; 281-310

Ritskes-Hoitinga J, Lemmens AG, Danse LHJC, Beynen AC. Phosphorus-induced nephrocalcinosis and kidney function in female rats. J Nutr 1989; 119:1423-1431

Ritskes-Hoitinga J, Mathot JNJJ, Danse LHJC, Beynen AC. Commercial rodent diets and nephrocalcinosis in weanling female rats. Lab Anim 1991; 25:126-132

Ritskes-Hoitinga J, Mathot JNJJ, Van Zutphen LFM, Beynen AC. Inbred strains of rats have differential sensitivity to dietary phosphorus-induced nephrocalcinosis. J Nutr 1992;


Ritskes-Hoitinga J, Mathot JNJJ, Lemmens AG, Danse LHJC, Meijer GW, Van Tintelen G, Beynen AC. Long-term phosphorus restriction prevents corticomedullary nephrocalcinosis and sustains reproductive performance but delays bone mineralization in rats. J Nutr 1993;


Ritskes-Hoitinga J, van het Hof KH, Kloots WJ, de Deckere EAM, van Amelsvoort JMM, Weststrate JA. Rat as a model to study postprandial effects in man. In Proceedings of The World Congress on Alternatives and Animal Use in the Life Sciences: Education, Research, Testing. Goldberg AM, van Zutphen LFM eds. Alternative methods in Toxicology and the Life Sciences, Series volume 11, 1995; 403-410

Ritskes-Hoitinga J, Meijers M, Timmer WG, Wiersma A, Meijer GW, Weststrate JA. Effects of two dietary fat levels and four dietary linoleic acid levels on mammary tumor development in Balb/c-MMTV mice under ad libitum feeding conditions. Nutr Cancer 1996; 25:161-172

Ritskes-Hoitinga J, Verschuren PM, Meijer GW, Wiersma A, van de Kooij AJ, Timmer WG, Blonk CG, Weststrate JA. The association of increasing dietary concentrations of fish oil with hepatotoxic effects and a higher degree of aorta atherosclerosis in the ad lib.-fed rabbit. Food Chem Toxicol 1998; 36:663-672

Ritskes-Hoitinga J, Grooten HNA, Wienk K, Peters M, Lemmens AG, Beynen AC. Lowering dietary phosphorus concentrations reduces kidney calcification, but does not adversely affect growth, mineral metabolism, and bone development in growing rabbits. Brit J Nutr in print

Roe FCJ. Historical histopathological control data for laboratory rodents: valuable treasure or worthless trash? Lab Anim 1994; 28:148-154

Sanders S, Ackroff K, Collier GH, Squibb R. Purified diets: some cautions about casein.

Physiol Behav 1984; 33:457-463

Schlingmann F, van de Weerd HA, Blom HJM, Baumans V, van Zutphen LFM. Behavioural differentation of mice housed on different cage floors. Proceedings of the fifth FELASA symposium; 1993 June 8-11; Brighton UK, Royal Society of Medicine Press 1994; 335-SGV Newsletter nr. 24 (spring 2001): 357

Speijers GJA. Voedingsvezel en haarballen. Proceedings of the NVP symposium “voeding en kwaliteit van proef en dier”, 1987; 79-86.

Spiteri NJ. Circadian patterning of feeding, drinking and activity during diurnal food access in rats. Physiol Behav 1982; 28:139-147

Stephan FK. Phase shifts of circadian rhythms in activity entrained to food access. Physiol Behav 1984; 32: 663-771

Strubbe JH, Gorissen J. Meal patterning in the lactating rat. Physiol Behav 1980; 25:775-777 Strubbe JH. Neuro-endocrine factors. In Food Intake and Energy Expenditure.

Westerterp-Plantenga MS, Fredrix EWHM, Steffens AB eds, CRC Press, London 1994a, 175-182 Strubbe JH. Circadian rhythms of food intake. In Food Intake and Energy Expenditure.

Westerterp-Plantenga MS, E.W.H.M. Fredrix EWHM, Steffens AB eds, CRC Press, London 1994b, 155-174

Strubbe JH. “Hunger, meals and obesity.” In Encyclopedia of Cognitive Science. Nadel L ed, Nature Publishing Group, London 2003

Strubbe JH, Alingh Prins AJ. Reduced insulin secretion after short-term food deprivation in rats plays a key role in the adaptive interaction of glucose and free fatty acid utilization.

Physiol Behav 1986; 37:441-445

Strubbe JH, Van Dijk G. Temporal organisation of feeding behavior and its interaction with regulation of energy balance. Neurosci Behav Rev 2002; 26:485-498

Strubbe JH, Keyser J, Dijkstra T, Alingh Prins AJ. Interaction between circadian and caloric control of feeding behavior in the rat. Physiol Behav 1986a; 36:489-493

Strubbe JH, Spiteri NJ, Alingh Prins A. Effects of skeleton photoperiod and food availability on the circadian pattern of feeding and drinking in rats. Physiol Behav 1986b; 36: 647-651 Strubbe JH, Alingh Prins AJ, Bruggink J, Steffens AB. Daily variation in of food-induced

changes in blood glucose and insulin in the rat and the control by the suprachiasmatic nucleus and the vagus nerve. J Auton Nerv Syst 1987; 20:113-119

Thon R, Lassen J, Kornerup Hansen A, Jegstrup I.M, Ritskes-Hoitinga J. Welfare evaluation of genetically modified mice in Denmark. An inventory study of the reports from 1998 to the Animal Experiments Inspectorate. Scand J Lab Anim Sci 2002; 29:45-55

Toates FM, Rowland NE eds. Feeding and Drinking. Amsterdam: Elsevier, Amsterdam 1987 Tobin G. Current concepts – Natural ingredient diets. Harlan Continuing Education

Conference, 2003 March 12 – 14; Vaals, The Netherlands.

Vachon C, Jones JD, Nadeau A, Savoie L. A rat model to study postprandial glucose and insulin responses to dietary fibers. Nutr Rep Int 1988; 37:1339-1348

Vermeulen JK, de Vries A, Schlingmann F, Remie R. Food deprivation: common sense or nonsense? Anim Technol 1997; 48:45-54

Vonk RJ, Van Doorn ABD, Strubbe JH. Bile secretion and bile composition in the freely moving unanaesthetized rat with a permanent biliary drainage: influence of food intake on bile flow. Clin Sci Mol Med 1978; 55:253-259

Zhou J, Moeller J, Ritskes-HoitingaJ, LarsenML, Austin RC, Falk E. Effects of vitamin supplementation and hyperhomocysteinemia on atherosclerosis in apoE-deficient mice.

Atherosclerosis 2003; 168(2):255-262

In document University of Groningen Nutrition and Animal Welfare Ritskes-Hoitinga, Merel; Strubbe, Jan H. (Page 26-31)

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